On Mon, Apr 9, 2012 at 7:17 PM, Julian Schmidt <julian_schm...@chipmusik.de> wrote:
> setting the phase increment to an integer value solves the problem. > [...] > adding linear or cubic interpolation makes it a little better, but the > pulsing is still very audible. > [...] > The nearer i get to an integer phase increment, the slower the amplitude > of the harmonics is pulsating. at an integer value it stops. All of these findings support the hypothesis that it is an aliasing problem. So it doesn't need to have to do with phase wrapping. Saw wave and similarly discontinuous waveforms are particularly nasty when it comes to aliasing problems because the harmonics decay so slowly (amplitude of Nth harmonic = 1/N). I bet the reason why you had so little problems with the sine wave is because it was greatly oversampled (that is, the highest frequency, in this case the fundamental frequency, is less than sampling frequency / 2). Do a mental check on what the bandwidth of your wavetable is, and whether you will get aliasing by playing back the wavetable at a different rate than 1:1 and by resampling it to the target sampling frequency. -olli -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
